This invention relates to temperature stabilization in a servo system, and more particularly to such stabilization in a fluid damped servo system.
A fluid filled force balance type instrument such as the servo accelerometer disclosed in U.S. Pat. No. 3,331,253 for an accelerometer and sensing assembly utilizes the fluid not only for flotation and relief of forces at the support points for the inertial mass, but also to provide viscous damping forces for the motion of the inertial mass. Most flotation fluids having acceptable densities for flotation purposes are also susceptable to considerable change in viscosity over normal operating temperature ranges. As a consequence, desirable servo characteristics set at room temperature may change appreciably at the high and low ends of a specified temperature range. To maintain a given natural frequency or damping ratio, for example, requires an increase in servo gain for a decrease in temperature as the viscosity of the flotation fluid becomes greater with decreasing temperature. Apparatus is therefore desirable which will provide an increase in the servo system gain as temperature decreases, and a decrease in servo system gain as temperature increases. Such apparatus ideally would allow independent setting of necessary gain at room temperature and necessary gain change over the temperature range to maintain the desired operating characteristics.